Stretch draw press with power positioned stretch unit



S. M. DOLNEY Oct. 18, 1966 STRETCH DRAW PRESS WITH POWER POSITIONED STRETCH UNIT 8 SheetsSheet 1 Filed April 29, 1964 INVENTOR. 77/- 4 A BY Oct. 18, 1966 s. M. DOLNEY 3,279,232

STRETCH DRAW PRESS WITH POWER POSITIONED STRETCH UNIT Filed April 29, 1964 8 Sheets-Sheet 2 I NVEN TOR ATTORNEY.

S. M. DOLNEY Oct. 18, 1966 STRETCH DRAW PRESS WITH POWER POSITIONED STRETCH UNIT 8 Sheets-Sheet 5 Filed April 29, 1964 INVENTOR. B 7/- W I @ATTORNEY.

S. M. DOLNEY Get. 18, T966 STRETCH DRAW PRESS WITH POWER POSITIONED STRETCH UNIT 8 Sheets-Sheet 4;

Filed April 29, 1964 (llll'l lNl Elg TOR.

45 AT TORNEY.

S. M. DOLNEY Oct. 18, 1966 STRETCH DRAW PRESS WITH POWER POSITIONED STRETCH UNIT 8 Sheets-Sheet 6 Filed April 29, 1964 INVENTOR.

427/- AMW Oct. 18, 1966 s. M. DOLNEY 9 3 STRETCH DRAW PRESS WITH POWER POSITIONED STRETCH UNIT Filed April 29, 1964 8 Sheets-Sheet INVENTOR.

M 7% BY Q ATTORNEY.

Oct. 18, 1966 s. M. DOLNEY 3,279,321

STRETCH DRAW PRESS WITH POWER POSITIONED STRETCH UNIT Filed April 29, 1964 8 Sheets-Sheet 8 13 E \2 a; 86 5 j I F" /6 F2 /5 United States Patent 3,279,232 STRETCH DRAW PRESS WliTH PUWER POST- TIONED STRETCH UNIT Stanley M. Dolney, Parma, Ohio, assignor to The Cyrrl Bath Company, Solon, Ohio, a corporation of Ohio Filed Apr. 29, 1964, Ser. No. 363,463 8 Claims. (Cl. 72-297) This invention relates to an improved combined die drawing and stretch forming press and particularly to a new and improved arrangement by which the stretch forming units of the press can be moved along the bolster of the press toward and away from the midportion of the die path to selected adjusted positions.

For purposes of illustration the invention is hereinafter described in connection with a draw die press and prestretch unit combination such as disclosed in United States Letters Patent of Cyril I. Bath, No. 3,116,780, patented J an. 7, 1964, and entitled Prestretch Fixture and Combination Thereof with Drawing Die Press, its use in other combinations being apparent from the illustrative example.

A principal object of the present invention is to provide on each stretch unit a power driven hoist mechanism which is antifrictionally supported on the bolster and by which, when the unit is unbolted from the bolster of the press, the unit can be lifted readily and rapidly clear of the bolster, and supported by the hoist mechanism so that the unit can be moved readily with very small power requirement to selected locations toward and away from the midportion of the die space, and when in the desired adjusted position, the unit can be lowered onto the bolster block and bolted or otherwise fastened in place.

Another object is to provide a power drive for moving two stretch units independently of each other to adjusted position While they are thus antifrictionally supported, and to constrain them to move in lineal paths parallel to their original installed positions in proper alignment for stretchmg.

Still another object is to provide spacing blocks by which the units can be held spaced apart from each other in a desired adjusted position while, at the same time, the blocks provide a solid support for a drawing die, at a level above the bolster and in position for cooperation with the stretch units and the matching die on the ram of the press.

Various other objects and advantages will become apparent from the following description wherein reference is made to the drawings, in which FIGURE 1 is a front elevation of a combination of a draw die press and stretch forming prestretch units em- 'bodying the principles of the present invention;

FIG. 2 is a right end elevation of the structure illustrated in FIG. 1;

FIG. 3 is a top plan view of one of the stretch units, part thereof being shown in section;

FIG. 4 is a front end elevation of the stretch unit illustrated in FIG. 3;

FIG. 5 is a right end elevation of the stretch unit illustrated in FIG. 3, part thereof being shown in section;

FIG. 6 is an enlarged cross-sectional view of the stretch unit illustrated in FIGURES 1 through 5, showing the operating parts thereof, and is taken on line 6-6 of FIG. 3;

FIG. 7 is a top plan view of the bolster of the press with the stretch units thereon, part only of the units being shown for clearness in illustration, and the units being shown in a position moved inwardly closer to the midportion of the die space than as illustrated in FIG. 1;

FIG. 8 is a vertical sectional View of the structure illustrated in FIG. 7 and is taken on line 8-8 thereof;

FIG. 9 is a vertical sectional view of the structure illustrated in FIG. 7 and is taken on line 9-9 thereof;

3,27%,232 Patented Oct. 18, 1966 FIG. 10 is a right side elevation of the structure illustrated in FIG. 7;

FIG. 11 is an enlarged fragmentary vertical sectional view taken on the line 11-11 in FIG. 7;

FIG. 12 is an enlarged vertical sectional structure illustrated in FIG. 11, taken on line 12-12 thereof;

FIG. 13 is an enlarged fragmentary vertical sectional view taken on the line 13-13 of FIG. 11, part thereof being shown in elevation for clearness in illustration;

FIG. 14 is an enlarged fragmentary vertical longitudinal sectional view taken on the line 14-14 of FIG. 7, part thereof being shown in elevation for clearness in illustration.

FIG. 15 is an enlarged cross-sectional view taken on the line 15-15 in FIG. 14;

FIG. 16 is an enlarged fragmentary vertical sectional view taken on line 16-16 of FIG. 7, showing the guide bars and their cooperation with the bolster of the press; and

FIG. 17 is a schematic showing of the hydraulic and control system of the invention.

Referring to the drawings, the invention is shown as incorporated in a conventional hydraulic press indicated generally at 1, comprising a bed 2 with upright corner guide posts 3 arranged at the four corners thereof and supporting a crown on which is carried a piston and cylinder assemblage 4, including a cylinder 5 and a piston 6 having a rod 7. The press has a ram 8 which is reciprocable vertically while guided by the corner posts 3 and which is connected to the rod 7 for reciprocation thereby. Pressure fluid is supplied to the piston and cylinder assemblage 4 by a suitable pump 9 driven by an electric motor M and controlled by conventional reversing valve V.

In the form illustrated, two identical stretch units 10 are provided, and are carried by the bed 2. For this purpose, a modified bolster 12 is mounted on the bed 2. Suitable spacing and supporting blocks, as will later be described, are arranged on the bolster and supports a male drawing die D1. A matching female drawing die D2 is carried by the ram 8. The dies D1 and D2 are conventional drawing dies.

The stretch units 10 are the same in form and function, and hence only one of them is described'in detail herein. Referring to FIGURES 3 through 6, each stretch unit 11] comprises a base plate 13, on the ends of which are mounted guide supports 14 which support upright guides 15. The guides 15 have upright guide faces 16 facing inwardly of the unit in a direction forwardly and rearwardly of the bed and upright guide faces 17 at right angles to the faces 16. Mounted for vertical reciprocation in the guideways formed by these surfaces is an elevator 20 which is guided thereby for movement upwardly and downwardly while the elevator itself remains parallel to its starting position. For moving the elevator 20 upwardly and downwardly, suitable piston and cylinder assemblages 21 are provided, one at each end of the unit 10. Each assemblage 21 comprises a cylinder 22 mounted in fixed position on the elevator 20, a piston 23 reciprocable in the cylinder and having a piston rod 24. The cylinder 22 is arranged so that the piston rod extends downwardly and at its lower end carries a tongue 25 by which it is pivotally connected by horizontal pivot 26 to a suitable yoke 27. The yoke is fixedly secured to the base of guide support 14. Thus, upon introduction of the hydraulic pressure fluid to the rod ends of the cylinder 22 they move the elevator 20 downwardly and by the introduction of fluid t-o the head end of the cylinder they move the elevator 20 upwardly. These movements are under yieldable hydraulic pressure and controllable independently of the operation and control of the ram piston and cylinder assemblage 4.

In order to stretch the stock into a range above its elastic limit independently of the dies D1 and D2, suitable gripper heads are provided, one for each unit it). Each head comprises an elongated body 31, which end wise extends forwardly and rearwardly of the press bed and thus transversely of the tensioning dimension. Each head has complementary gripping jaws 32 and 32a which are cooperable with the wedge surfaces 33 and 34 so that when the jaws are moved toward the dies they can approach each other and grip the stock. Each pair of jaws extends substantially the full length of the associated head 30.

In order to close the jaws, each head 3%) is provided with a plurality of piston and cylinder assemblages 35, each of which includes a cylinder 36 and a piston 37 reciprocable therein and having a piston rod 38. The rods 38 are connected by enlarged heads 39 to the jaws 32 and 32a for causing the jaws to move along the wedge surfaces 33 and 34 toward and away from the dies for moving the jaws together and apart, respectively. The assemblages are fed by a common manifold 41 connected by individual ducts 42 to the rod ends of the cylinders 36, and a common manifold 43 connected by individual ducts to the head ends of the cylinders 36. Thus all jaw pistons can be operated concurrently.

The stretch head 30 of each unit is arranged so that it can be moved toward and away from the dies under yieldable resistance by hydraulic pressure so as to tension the stock above the elastic limit. For this purpose each head is mounted on a carriage or support which is mounted on the elevator 20 for movement toward and away from the adjacent ends of the die. The carriage 50 is moved by a stretch forming assemblage 52 which includes a body 54 having parallel cylinders 55 therein. The body 54 is mounted at its ends on the elevator 26 by trunnion 57 [for rocking about a horizontal axis forwardly and rearwardly of the press bed. The trunnions are rockably supported by suitable upright supports 58 and 59 which are rigid with elevator 20. Each cylinder 55 has a piston 60 with a rod 61 having an eye at its outer end for receiving a pivot pin 63 by which it is pivotally connected to an associated rocking link 64. Two such links are provided for the six cylinders illustrated. The lower end of the links are connected by pivots 65 to bearing blocks 66 which are in fixed relation to the elevator. At their upper ends the links are connected by pivots 67 to bearing portions on the carriage 50 for rocking relative to the carriage.

The elevator is provided with upwardly facing track- Ways 70 extending toward and away from the dies. The carriage is provided with rollers 71 which normally rest on the trackway. Pressure fluid is supplied to the head ends of the cylinder 55 which drives the pistons, causing the link 64 to swing, clockwise in FIG. 6, about the axis of the pivots 65, and thereby pull the carriages to the right for tensioning the stock. On reversal of the assemblages 52, the carriage 50 is driven toward the dies. The unit is more fully described in the above identified patent. The piston and cylinder assemblages are supplied with pressure fluid by conventional pumps and motors with suitable control valves as set forth in the patent.

Other types of stretch forming units may be employed, the above one being shown for purposes of illustration only. The details thereof form no part of the present invention, the important feature of the present invention being that, whatever stretch unit is employed, it can be moved bodily in assembled condition, as a unit, to different locations on the bolster.

The detailed description of a unit is given to impart some idea of the mass of a stretch unit. For example, a unit having a gripping head 72 inches long, forwardly and rearwardly of the press bed, for gripping metal sheets 72 inches wide, weighs about seven tons, and units in the range of from .four to ten tons in weight, dependent upon the maximum width of sheet to be gripped, are not uncommon. Generally these units must be adjusted toward and away from the midportion of the die space in a direction longitudinally of the bolster blocks or in a direction from left to right in FIG. 1, to different operating positions to meet the various die and sheet length requirements. The units shown are of a proper size to pass between the upright corner posts 3 so that they can be moved into the die space beneath the ram in close proximity to each other and retracted from the die space, the amount of retraction possible being limited only by the length of the bolster block employed in the particular press.

For a stretch unit weighing approximately seven tons, the time heretofore required to move the units from one position to another on the bolster was about four hours. The moving was usually done by handjacks of the hydraulic or mechanical type, a number of jacks and men being required to move a unit toward, and spot it accurately in its new adjusted position. However, it quite often happens that a single press will be used for making successive short runs of different parts, and after each relatively short run, it may be necessary to change dies and adjust the units accordingly. Obviously, four hours for each run would be a very expensive operation. In accordance with the present invention, each unit can be moved to, and spotted in, a new adjusted position in a few seconds, by a single workman using very light power means.

The improvement is best illustrated in FIGURE 7 through FIGURE 16. As there shown, the bolster 12 of the press is provided with the usual transverse T-slots 70 extending forwardly and rearwardly of the press bed and longitudinal T-slots 71 extending at right angles to the slots 70. Since the mountings or both units 10 are the same in form and function, only the mounting of one will be described in detail. Mounted on the base plate 13 of a stretch unit 10 are piston and cylinder assemblages 72. These piston and cylinder assemblages preferably number four to the unit and are arranged in pairs. The pairs are spaced forwardly and rtarwardly of the bolster block equidistantly from the midportion of the unit. The assemblages of each pair are aligned endwise of the bolster. Each assemblage 72 compirses a cylinder 73 rigidly fastened to the base plate 13 of the unit on the upper face of the plate and a piston 74 reciprocable therein and having a depending rod 75 extending through a suitable hole in the plate 13. The depending rod is arranged to drive a vertically movable supporting block 76 which is slidable vertically in a passageway in the plate 13 and extends below the underface of the plate 13. All of the assemblages 72 of each unit 10 are operable concurrently.

The bolster block, in turn, is provided with longitudinal supporting ways or channels 78 which extend from the outer end of the block adjacent the unit 10 toward the midportion of the block. The channels terminate at their inner ends in sufiiciently closely spaced relation to the midportion of the die space to permit movement of the two stretch units substantially into contact with each other at the midportion of the die space.

The bottom wall of each supporting way 78 is surfaced with hardened steel bearing plate 80 which extends the full length of the ways.

Mounted on the bottom of each of the blocks 76 are antifriction means which preferably comprise a set 81 of recirculating roller bearings employing rollers 82. The recirculating roller hearing may be of the type disclosed in United States Letters Patent No. 3,003,828, issued Oct. 10, 1961, to James A. Stark and entitled Recirculating Bearing. Suitable brackets 83 are mounted on the ends of the base plates 13 and carry at their lower ends the usual wipers 84 for wiping the surfaces of the bearing plates 80 during the adjustment of the unit.

With this arrangement, when it is desirable to adjust a unit, all that is necessary is to loosen the usual tie bolts which anchor the unit 10 to the bolster plate, introduce pressure fluid into the head ends of the cylinder assemblage 72 and thereby depress the blocks 76 and apply the recirculating roller bearing assemblages 81 against the bearing plate 80 in the bottom of the supporting ways with sufiicient power to lift bodily the stretch unit, including the plate 13 and all of the mechanisms supported thereon, about one-eighth of an inch clear of the bolster 12. While in this lifted condition, the unit can be pushed very readily toward and away from the die space to the desired position without great physical effort, the rollers rolling along the supporting ways freely.

However, it is desirable that adjustment be made with power means. For this purpose, a fixed housing 86, having vertical guideways 87 therein, and partially closed at the end by guideways 88 is secured in depending relation to the bottom of each base plate 13 of each unit. Mounted within the housing 86 is a follower 89 which is free to move vertically relative to housing 86 and plate 13, but is restrained from rotation by the guideways 87 and from endwise movement relative to the plate 13 by the end guideways 88. The follower 89 is mounted in driving relation on a screw 90 which is driven through a suitable gear reduction 91 by a reversible electric motor 92.

The screw 90 is mounted in suitable bearings 93 in a channel 94 in the bolster 12. The channel 94 extends longitudinally on the bolster and is preferably located midway bet-ween the front and rear of the bolster 12. Generally a motor of three-quarter horsepower is adequate for rapidly moving the entire unit while the unit is thus antifrictionally supported.

With this arrangement, all that is necessary for adjusting a unit 10 to a desired position, is to unbolt the normal tie bolts engaging the various T-slots in the bolster and holding the unit in operating position. Upon release of these tie bolts, the assemblages 72 operated so as to force the recirculating bearings downwardly against the strip 80 with suflicient force to lift the unit clear of the bolster 12, supports it antifrictionally in lifted condition. Thereupon the motor 92 is started and drives the unit to the selected position. The unit 10 generally is not lifted more than one-eighth of an inch above the bolster 12 and the rise and fall of the follower 89 relative to the housing 86 compensates for this difference in elevation and prevents binding of the screw 90.

In order to guide the unit 10 as it is moved forwardly or rearwardly longitudinally of the bolster 12, suitable guide slots 96 are provided. As best illustrated in FIG- URE 16, these slots may be T-slots useful for other purposes as well as for guiding. The plate 13 is provided with depending guides 97 which are held in place by bolts 98. These guides are guided by the walls defining the leg portions of the T-slots 96 and reduce any tendency of the unit and blocks 76 to cock and bind.

In order to bolt the unit 10 to the bolster 12, the usual tie bolts 98, carrying T-nuts 99 operable in the T-slots of the bolster 12 are provided. However, to assure that the bolts 98 are sufficiently loose to permit lifting the unit when the assemblages 72 are operated, C-washers 100 are pivotally mounted on the plate 13. Upon slight loosening of the bolts 98, the washers 100 can be swung from beneath the heads of the bolts 98. The washers 100 are of greater thickness than the total lift of the unit 10 by the assemblages 72. Hence, when all of the washers are in inoperative position, the unit 10 is free to be lifted and moved.

In order to support the die D1 effectively on the bolster 12, above the normal level of the bolster face, a plurality of large hollow fabricated, structurally strong metal blocks 101 are provided. The blocks are made in units of different sizes and have lower faces which rest firmly in juxtaposition with the upper face of the bolster 12 along the entire length of the blocks forwardly and rearwardly of the bolster. The blocks have upright sides such that they can be juxtaposed against each other in a direction longitudinally of the bolster 12 and thus hold each other in place in the tensioning directions. The upper surfaces of the blocks are parallel to their lower surfaces. When the blocks 101 are assembled between the units, they define an upper surface for supporting the entire undersurface of the die D1. The positions of the units are selected so that the blocks fill the space between the units When the latter are moved to adjusted position. The blocks may be placed on the bolster so as to substantially fill the space between the units, and one of both or the units then moved a fraction of an inch to close against the end blocks. Some fractional width blocks may be provided for completely filling the space between the units with the units spaced a proper distance apart for the particular die. Blocks of this character with a die secured thereto, provide a very rigid die support. The blocks can be held by the units in proper operating position, but, if desired, end positioning bolts or clamps may be used to bind them to the bolster to prevent any possibility of shifting of the blocks forwardly and rearwardly of the bolster or press. Sets of blocks for different die heights may also be provided for meeting the various conditions that may arise in the field or to place the die in the optimum position, for the rise and fall of the head.

For operating the piston and cylinder assemblages'72, the four assemblages of each unit may be connected in parallel, as illustrated in FIGURE 17. Hydraulic fluid may be supplied to the parallel connected units from the hydraulic source for the assemblages 52, if desired. On the other hand, the pressure fluid may be supplied by a pump 102, driven by a motor 103, and connected through conventional individual valves 104. The hydraulic circuits of the stretch units themselves form no part of the present invention and hence are not illustrated, but a full disclosure can be found in the above identified patent.

Having thus described my invention, I claim:

1. A sheet metal stretching apparatus comprising stretch forming piston and cylinder means, a gripping head connected thereto, gripping jaws carried by the head, power operated mechanism for operating the jaws, a frame supporting said means, head, and power operated mechanism for bodily movement with the frame as an assembled operable unit, a supporting base having a load supporting face normally supporting the unit and having upwardly facing parallel load supporting ways, supports mounted on the frame for movement relative thereto in directions toward and away from said supporting base and aligned with the ways, antifriction means carried by the supports, respectively, said supports being operable to hold the antifriction means in contact with the ways, power operable hoists means connected to the frame and. supports operable when connected to a predetermined source of power, to apply sulficient hoisting force against the supports, to lift the unit bodily clear of the supporting face and transfer its weight, through the supports and antifr iction means, onto the ways and thereby antifrictionally supporting the unit for movement along the ways, and means for connecting the hoist means to and disconnecting the hoist means from said predetermined source of power.

2. An apparatus according to claim 1 wherein a power drive mechanism drivingly interconnects the base and unit and is operable, when connected to a source of power, to drive the unit in opposite directions, selectively, along the ways while the unit is supported by the hoist means.

3. An apparatus according to claim 1 wherein the base has guideways parallel to said ways, and guides are carried by the unit and operate in said guideways to maintain the unit parallel to its starting position as it is moved along said guideways.

4. An apparatus according to claim 1 wherein the hoist means are a plurality of upright hydraulic piston and cylinder assemblages mounted on the unit and spaced horizontally from each other, the supports are separate load bearing members operatively connected to the assemblages, respectively, and having downwardly facing undersurfaces, respectively, and the antifriction means are sets of recirculating roller bearings juxtaposed against said undersurfaces with the rollers in rolling engagement with the ways.

5. An apparatus according to claim 1 wherein the supporting base has T-slots extending parallel to said ways, tie bolts are mounted on the unit in alignment with the T-slots, T-nuts are in threaded engagement with the bolts, respectively, disposed in the slots for clamping the units in place when the units are resting on said load supporting face, the heads of the bolts being positioned for exerting downward pressure against upwardly exposed horizontal surface areas, respectively, of the unit, washers disposed between the heads and the associated areas, respectively, each washer being open at one side so as to be receivable edgewise, open side foremost, between the head of the associated bolt and the associated area, and removable edgewise in the opposite direction, and the thickness of each washer being greater than the distance the unit must be lifted to be antifrictionally supported.

6. An apparatus according to claim 5 wherein each washer is pivotally connected to the unit for swinging about an upright axis into and out of position between its associated bolt head and horizontal surface area.

7. A combined die drawing and stretch press comprising a press frame, a horizontal bolster block carried thereby, a power driven ram movable vertically toward and away from the bolster, a stretch unit complete in and of itself, normally resting on the upper face of the bolster, power operable hoist means on the unit, antifriction means connected to the hoist means and applicable against the bolster thereby with sufficient force to transfer the weight of the unit to the antifniction means and lift and antifrictionally support the unit clear of said upper face when the hoist means is connected to a source of power, power means for moving the unit horizontally in opposite directions in a path while so antifrictionally supported, means for connecting the hoist means to, and disconnecting the hoist means from, a source of power, and means for connecting the power means to, and disconnecting the power means from, a source of power.

8. A combined die drawing and stretch press comprising a press frame, a horizontal bolster thereon, a power driven ram movable vertically toward and away from the bolster, a pair of stretch units, each complete in and of itself, normally resting on the upper face of the bolster, power operable hoist means on the units, respectively, antifriction means connected to the hoist means, respectively, and applicable against the bolster by the associated hoist means with sufiicient force to transfer the weight of the associated unit to the antifriction means and lift and antifrictionally support the unit clear of said upper face when the hoist means is connected to a source of power, driving power means operable for moving the units, when they are antifrictionally supported, relatively toward and away from each other, means for connecting and disconnecting the hoist means from a source of power, means for connecting and disconnecting the driving power means to a source of power, a plurality of diesupporting spacing blocks disposed on said upper face and arranged in a row extending from one unit to the other, said blocks being juxtaposed adjacent blocks against each other, the outerend faces of the end blocks of the row being juxtaposed against the units, respectively, and con straining the units from movement relatively toward each other, and said blocks being of equal height and providing at their top faces a planar die supporting surface.

References Cited by the Examiner UNITED STATES PATENTS 1/1942 Oeckl 72297 12/1963 Maize 72-296, 

1. A SHEET METAL STRETCHING APPARATUS COMPRISING STRETCH FORMING POISTON AND CYLINDER MEANS, A GRIPPING HEAD CONNECTED THERETO, GRIPPING JAWS CARRIED BY THE HEAD, POWER OPERATED MECHANISM FOR OPERATING THE JAWS, A FRAME SUPPORTING SAID MEANS, HEAD, AND POWER OPEATED MECHANISM FOR BODILY MOVEMENT WITH THE FRAME AS AN ASSEMBLED OPERABLE UNIT, A SUPPORTING BASE HAVING A LOAD SUPPORTING FACE NORMALLY SUPPORTING THE UNIT AND HAVING UPWARD LY FACING PARALLEL LOAD SUPPORTING WAYS, SUPPORTS MOUNTED ON THE FRAME FOR MOVEMENT RELATIVE THERETO IN DIRECTIONS TOWARD AND AWAY FROM SAID SUPPORTING BASE AND ALIGNED WITH THE WAYS, ANTIFRICTION MEANS CARRIED BY THE SUPPORTS, RESPECTIVELY, SAID SUPPORTS BEING OPERABLE TO HOLD THE ANTIFRICTION MEANS IN CONTACT WITH THE WAYS, POWER OPERABLE HOISTS MEANS CONNECTED TO THE FRAME AND SUPPORTS OPERABLE WHEN CONNECTED TO THE FRAME AND SUPPORTS OPERTO APPLY SUFFICIENT HOISTING FORCE AGAINST THE SUPPORTS, TO LIFT THE UNIT BODILY CLEAR OF THE SUPPORTING FACE AND TRANSFER ITS WEIGHT, THROUGH THE SUPPORTS AND ANTIFRICTION MEANS, ONTO THE WAYS AND THEREBY ANTIFRICTIONALLY SUPPORTING THE UNIT FOR MOVEMENT ALONGTHE WAYS, AND MEANS FOR CONNECTING THE HOIST MEANS TO AN DISCONNECTING THE HOIST MEANS FROM SADI PREDETERMINED SOURCE OF POWER. 